1. Statement of the Technical Field
The inventive arrangements relate to reflectors that focus electromagnetic energy in applications such as, but not limited to, radio-frequency (RF) antennae, solar collectors, cameras and other optical devices, etc.
2. Description of the Related Art
Reflectors used in RF antennas, solar collectors, optical devices, etc. are usually shaped so as to focus electromagnetic energy at a particular point or area, or in a particular direction, such as at an antenna feed system mounted on or proximate the reflector. Reflectors of this kind are commonly shaped to have a three-dimensional curved surface, such as a parabolic surface. Reflectors are usually configured in a solid or a mesh configuration. A solid reflector may comprise, for example, a rigid frame with a solid reflective skin mounted thereon. Wire mesh reflectors typically comprise a flexible metallic mesh supported on a framework of rigid, radially-oriented ribs.
Solid reflectors generally provide higher performance than mesh reflectors, i.e., a solid reflector usually will focus the electromagnetic energy incident thereupon with less loss as compared to a mesh reflector of the same or similar size. Moreover, the mesh of a mesh reflector may require individual positional or cord adjustments at hundreds or even thousands of locations thereon during its assembly and after deployment to achieve a required performance level. Even with such time-consuming and labor-intensive adjustments, it can be difficult to achieve a surface roughness, i.e., deviation from an ideal surface profile, of less that 0.010-inch (0.25 mm) in a mesh reflector. A surface roughness of 0.010-inch or less is generally required when the reflector is used to focus high-frequency RF signals such as Ka and Ku-band transmissions. Thus, the performance of wire-mesh reflectors is usually limited in such applications.
Mesh reflectors, however, can have advantages relating their stored volume. In particular, mesh reflectors usually can be folded into a compact configuration, thereby facilitating storage in relatively small volumes. A typical solid reflector, by contrast, is not foldable, and therefore has a larger ratio of stowed-to-deployed volume than a mesh reflector having an aperture of comparable size. This characteristic can be particularly disadvantageous in satellite and other space-based applications due to limitations on the size of the fairings in which the reflectors are typically stowed prior to deployment. Solid reflectors with apertures greater than 3.5 m typically need to be partitioned to fit in the fairing volume, making mesh reflectors more attractive for larger aperture reflectors. Thus, solid reflectors having apertures greater 3.5 meters (11.5 feet) diameter are not commonly used in space-based applications, or in airborne and other mobile applications.